Over 25% of China's surface water is impure according to the country's Ministry of Environmental Protection.
Admitting that China still faces "severe challenges" in pollution control, environmental monitoring authorities said 26.4 percent of the country's surface water samples were at levels IV and V-only good for industrial use and farm irrigation.
A Xinhua report quoted a document posted on the ministry's website as saying that China classifies water quality into six levels, ranging from level I, which is good for drinking, to level VI, which is too polluted for any purposes.
Levels I to III means the water can be used for drinking, swimming and fish farming.
The ministry did not provide details on how the water quality was tested.
The ministry said in the document 189 cities out of the 443 cities monitored had suffered from acid rain pollution.